Electric field-driven building blocks for introducing multiple gradients to hydrogels.

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Nanotechnology

Background:

• Gradient biomaterials better mimic native tissues but are challenging to fabricate.
• Existing methods require specialized equipment and are limited in scope.
• Creating hydrogels with multiple gradients is a significant hurdle in tissue engineering.

Purpose of the Study:

• To develop a versatile and controllable strategy for introducing multiple gradients into hydrogels.
• To utilize beta-sheet rich silk nanofibers (BSNF) as building blocks for gradient fabrication.
• To demonstrate the application of these gradient hydrogels in controlling tissue regeneration.

Main Methods:

• BSNF were incorporated into hydrogel systems and subjected to an electric field during crosslinking.
• Migration and stagnation of BSNF under electric field and solution-viscosity control achieved gradient distribution.
• Silk-based hydrogels with mechanical and orientation gradients were fabricated.
• The strategy was tested for its universality across different hydrogel types (e.g., Gelatin, NIPAM).

Main Results:

• Achieved tunable gradient distribution of BSNF, leading to controllable mechanical gradients.
• Simultaneously created orientation gradients in the hydrogels.
• Demonstrated successful loading of different cargos onto BSNF for multi-gradient cues.
• Fabricated silk-based hydrogels that promoted chondrogenic-osteogenic differentiation and in vivo osteochondral tissue regeneration.

Conclusions:

• The crosslinking-electric field strategy offers a versatile and highly controllable method for creating complex gradient biomaterials.
• BSNF serve as multifunctional building blocks applicable to various hydrogel systems.
• This approach holds significant potential for advancing complex tissue engineering and regenerating interfacial tissues.